The damping of electrons of the \( \gamma \)  band, which is defined by
\(\Gamma _ \gamma \) , is obtained from the electron Green function[1]}
expressed as
\(G_ \gamma ( \mathbf {k}, i \omega _n)^{-1} & = &i \omega _n - E_{ \gamma , \mathbf {k}}+ \mu + i \Gamma _{ \gamma }\; , \\\Gamma _{ \gamma } & = & \Gamma + \Gamma _{\rm ph}^{ \gamma }\; ,\) 
